The following data pertain to activity (in units) and actual utilities cost for three recent years: using the high-low method, what is the variable cost per unit for utilities?
a) (Total cost at highest activity - Total cost at lowest activity) / (Highest activity - Lowest activity)
b) (Total cost at highest activity + Total cost at lowest activity) / (Highest activity - Lowest activity)
c) (Total cost at highest activity - Total cost at lowest activity) / (Highest activity + Lowest activity)
d) (Total cost at highest activity + Total cost at lowest activity) / (Highest activity + Lowest activity)
